Chlorine dioxide (ClO2) is a yellow orange gas at normal temperature and pressure and has an irritating and spicy taste similar to a mixture of chlorine and ozone. The boiling point is 11° C., the freezing point is −59° C., and the gaseous density is 3.09 g/m3 at 11° C. Gaseous ClO2 is unstable. Exposure of gaseous CIO2 to light or organic matter at high concentration will cause it to decompose violently and produce oxygen and chlorine. Normally it must be produced at the mill near its point of application. It is more stable when diluted to lower than 12% volume content with air or steam at atmospheric temperature or in the state of a low-temperature water solution. ClO2 is a strong oxidizer and can be used as a bleaching agent for pulp and textiles, and as water treatment agent, new air purifying freshener, and a disinfection, sterilizing, deodorizing agent for food, epidemic prevention, hygiene, etc.
At present, the main methods of producing chlorine dioxide include the methanol method and the integrated method. The methanol method uses methanol, sulfuric acid, and sodium chlorate as raw materials, and a vertical generator is used to produce chlorine dioxide. The chlorine dioxide product has a large moisture content of up to 80% (w/w) or more, and contains a small amount of chlorine. The integrated method uses hydrochloric acid and sodium chlorate as raw materials and either a vertical generator or horizontal generator can be used, but the chlorine dioxide gas contains a lot of chlorine, and the molar ratio of chlorine dioxide to chlorine is 2:1. For the use areas with high purity requirements (such as sodium chlorite preparation, food and medicine area, etc.), the purity of chlorine dioxide produced by the above two preparation methods cannot meet the use requirements.
In addition, chlorine dioxide product produced by common industrial chlorine dioxide preparation device are pumped to the final use areas in the form of low-temperature chlorine dioxide solution, not supplied in the form of gas.
Accordingly, an improved process and apparatus for producing high-purity chlorine dioxide gas may be beneficial.